262 research outputs found

    Participatory analysis for adaptation to climate change in Mediterranean agricultural systems: possible choices in process design (versão Pre Print)

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    There is an increasing call for local measures to adapt to climate change, based on foresight analyses in collaboration with actors. However, such analyses involve many challenges, particularly because the actors concerned may not consider climate change to be an urgent concern. This paper examines the methodological choices made by three research teams in the design and implementation of participatory foresight analyses to explore agricultural and water management options for adaptation to climate change. Case studies were conducted in coastal areas of France, Morocco, and Portugal where the groundwater is intensively used for irrigation, the aquifers are at risk or are currently overexploited, and a serious agricultural crisis is underway. When designing the participatory processes, the researchers had to address four main issues: whether to avoid or prepare dialogue between actors whose relations may be limited or tense; how to select participants and get them involved; how to facilitate discussion of issues that the actors may not initially consider to be of great concern; and finally, how to design and use scenarios. In each case, most of the invited actors responded and met to discuss and evaluate a series of scenarios. Strategies were discussed at different levels, from farming practices to aquifer management. It was shown that such participatory analyses can be implemented in situations which may initially appear to be unfavourable. This was made possible by the flexibility in the methodological choices, in particular the possibility of framing the climate change issue in a broader agenda for discussion with the actors

    Chitosan encapsulation modulates the effect of capsaicin on the tight junctions of MDCK cells

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    Capsaicin has known pharmacological effects including the ability to reversibly open cellular tight junctions, among others. The aim of this study was to develop a strategy to enhance the paracellular transport of a substance with low permeability (FITC-dextran) across an epithelial cell monolayer via reversible opening of cellular tight junctions using a nanosystem comprised by capsaicin and of chitosan. We compared the biophysical properties of free capsaicin and capsaicin-loaded chitosan nanocapsules, including their cytotoxicity towards epithelial MDCK-C7 cells and their effect on the integrity of tight junctions, membrane permeability and cellular uptake. The cytotoxic response of MDCK-C7 cells to capsaicin at a concentration of 500 μM, which was evident for the free compound, is not observable following its encapsulation. The interaction between nanocapsules and the tight junctions of MDCK-C7 cells was investigated by impedance spectroscopy, digital holographic microscopy and structured illumination fluorescence microscopy. The nanocapsules modulated the interaction between capsaicin and tight junctions as shown by the different time profile of trans-epithelial electrical resistance and the enhanced permeability of monolayers incubated with FITC-dextran. Structured illumination fluorescence microscopy showed that the nanocapsules were internalized by MDCK-C7 cells. The capsaicin-loaded nanocapsules could be further developed as drug nanocarriers with enhanced epithelial permeability

    The effect of polymer/plasticiser ratio in film forming solutions on the properties of chitosan films

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    In this work physical-chemical properties of chitosan/ glycerol film forming solutions (FFS) and the resulting films were analysed. Solutions were prepared using different concentrations of plasticising agent (glycerol) and chitosan. Films were produced by solvent casting and equilibrated in a controlled atmosphere. FFS water activity and rheological behaviour were determined. Films water content, solubility, water vapour and oxygen permeabilities, thickness, and mechanical and thermal properties were determined. Fourier transform infrared (FTIR) spectroscopy was also used to study the chitosan/glycerol interactions. Results demonstrate that FFS chitosan concentration influenced solutions consistency coefficient and this was related with differences in films water retention and structure. Plasticiser addition led to an increase in films moisture content, solubility and water vapour permeability, water affinity and structural changes. Films thermo-mechanical properties are significantly affected by both chitosan and glycerol addition. FTIR experiments confirm these results. This work highlights the importance of glycerol and water plasticisation in films properties.This work was supported by National Funds from FCT - Fundacao para a Ciencia e a Tecnologia, through project PEst-OE/EQB/LA0016/2011.Authors Joana F. Fundo, Andrea C. Galvis-Sanchez and Mafalda A. C. Quintas acknowledge FCT for research grants SFRH/ BD / 62176 / 2009, SFRH/BPD/37890/2007 and SFRH / BPD / 41715 / 2007, respectively

    Search for supersymmetric particles in scenarios with a gravitino LSP and stau NLSP

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    Sleptons, neutralinos and charginos were searched for in the context of scenarios where the lightest supersymmetric particle is the gravitino. It was assumed that the stau is the next-to-lightest supersymmetric particle. Data collected with the DELPHI detector at a centre-of-mass energy near 189 GeV were analysed combining the methods developed in previous searches at lower energies. No evidence for the production of these supersymmetric particles was found. Hence, limits were derived at 95% confidence level.Comment: 31 pages, 14 figure

    High catalytic activity of oriented 2.0.0 copper(I) oxide grown on graphene film

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    [EN] Metal oxide nanoparticles supported on graphene exhibit high catalytic activity for oxidation, reduction and coupling reactions. Here we show that pyrolysis at 900 C under inert atmosphere of copper(II) nitrate embedded in chitosan films affords 1.1.1 facet-oriented copper nanoplatelets supported on few-layered graphene. Oriented (1.1.1) copper nanoplatelets on graphene undergo spontaneous oxidation to render oriented (2.0.0) copper(I) oxide nanoplatelets on few-layered graphene. These films containing oriented copper(I) oxide exhibit as catalyst turnover numbers that can be three orders of magnitude higher for the Ullmann-type coupling, dehydrogenative coupling of dimethylphenylsilane with n-butanol and C–N cross-coupling than those of analogous unoriented graphene-supported copper(I) oxide nanoplatelets.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2012-32315) and Generalitat Valenciana (Prometeo 2013-019) is gratefully acknowledged. Partial financial support from European Union (Being Energy project) is also acknowledged. J.F.B. and I. E.-A. thank the Technical University of Valencia and the Spanish Ministry of Science for PhD scholarships, respectively. The authors are grateful to Mrs. Amparo Forneli for her assistance in the sample preparation and to Dr. Agouram Said from SCSIE, University of Valencia for the sample preparation and HRTEM characterization of samples. AD thanks University Grants Commission, New Delhi, for the award of Assistant Professorship under its Faculty Recharge Programme. AD also thanks Department of Science and Technology, India, for the financial support through Fast Track project (SB/FT/CS-166/2013) and the Generalidad Valenciana for financial aid supporting his stay at Valencia through the Prometeo programme. VP thanks UEFISCDI for financial support through PN-II-ID-PCE-2011-3-0060 project (275/2011).Primo Arnau, AM.; Esteve Adell, I.; Blandez Barradas, JF.; Amarajothi, D.; Alvaro Rodríguez, MM.; Candu, N.; Coman, SM.... (2015). High catalytic activity of oriented 2.0.0 copper(I) oxide grown on graphene film. Nature Communications. 6. https://doi.org/10.1038/ncomms9561S85616Huang, J. et al. Nanocomposites of size-controlled gold nanoparticles and graphene oxide: formation and applications in SERS and catalysis. Nanoscale 2, 2733–2738 (2010).Li, X., Wang, X., Song, S., Liu, D. & Zhang, H. Selectively deposited noble metal nanoparticles on fe3o4/graphene composites: stable, recyclable, and magnetically separable catalysts. Chem. Eur. J. 18, 7601–7760 (2012).Liang, Y. et al. Covalent hybrid of spinel manganese-cobalt oxide and graphene as advanced oxygen reduction electrocatalysts. J. Am. Chem. Soc. 134, 3517–3523 (2012).Ghanbarlou, H., Rowshanzamir, S., Kazeminasab, B. & Parnian, M. J. Non-precious metal nanoparticles supported on nitrogen-doped graphene as a promising catalyst for oxygen reduction reaction: synthesis, characterization and electrocatalytic performance. J. Power Sources 273, 981–989 (2015).Chu, H. et al. Ionic-liquid-assisted preparation of carbon nanotube-supported uniform noble metal nanoparticles and their enhanced catalytic performance. Adv. Funct. Mater. 20, 3747–3752 (2010).Ramulifho, T., Ozoemena, K. I., Modibedi, R. M., Jafta, C. J. & Mathe, M. K. Fast microwave-assisted solvothermal synthesis of metal nanoparticles (Pd, Ni, Sn) supported on sulfonated MWCNTs: Pd-based bimetallic catalysts for ethanol oxidation in alkaline medium. Electrochim. Acta 59, 310–320 (2012).Wang, Y., Zhao, Y., He, W., Yin, J. & Su, Y. Palladium nanoparticles supported on reduced graphene oxide: facile synthesis and highly efficient electrocatalytic performance for methanol oxidation. Thin Solid Films 544, 88–92 (2013).He, Y. et al. Metal nanoparticles supported graphene oxide 3D porous monoliths and their excellent catalytic activity. Mater. Chem. Phys. 134, 585–589 (2012).Li, Z. et al. One-pot synthesis of pd nanoparticle catalysts supported on n-doped carbon and application in the domino carbonylation. ACS Catal. 3, 839–845 (2013).Xiang, G., He, J., Li, T., Zhuang, J. & Wang, X. Rapid preparation of noble metal nanocrystals via facile coreduction with graphene oxide and their enhanced catalytic properties. Nanoscale 3, 3737–3742 (2011).Li, Z. et al. Experimental and DFT studies of gold nanoparticles supported on MgO(111) nano-sheets and their catalytic activity. Phys. Chem. Chem. Phys. 13, 2582–2589 (2011).Ding, M., Tang, Y. & Star, A. Understanding interfaces in metal-graphitic hybrid nanostructures. J. Phys. Chem. Lett. 4, 147–160 (2013).Wildgoose, G. G., Banks, C. E. & Compton, R. G. Metal nanoparticles and related materials supported on carbon nanotubes: methods and applications. Small 2, 182–193 (2006).Blandez, J. F., Primo, A., Asiri, A. M., Álvaro, M. & García, H. Copper nanoparticles supported on doped graphenes as catalyst for the dehydrogenative coupling of silanes and alcohols. Angew. Chem. Int. Ed. 53, 12581–12586 (2014).Yang, M. Q., Zhang, N., Pagliaro, M. & Xu, Y. J. Artificial photosynthesis over graphene-semiconductor composites. Are we getting better? Chem. Soc. Rev. 43, 8240–8254 (2014).Zhang, N., Zhang, Y. & Xu, Y. J. Recent progress on graphene-based photocatalysts: current status and future perspectives. Nanoscale 4, 5792–5813 (2012).Parga, A. L. V. de., Ha nacido una estrella. El grafeno. An. Quím. 107, 213–220 (2011).Rao, C. N. R., Sood, A. K., Subrahmanyam, K. S. & Govindaraj, A. Graphene: the new two-dimensional nanomaterial. Angew. Chem. Int. Ed. 48, 7752–7777 (2009).Sun, T. et al. Facile and green synthesis of palladium nanoparticles-graphene-carbon nanotube material with high catalytic activity. Nature 3, 1–6 (2013).Yoo, E. et al. Enhanced electrocatalytic activity of Pt subnanoclusters on graphene nanosheet surface. Nano Lett. 9, 2255–2259 (2009).Jin, X. et al. Lattice-matched bimetallic CuPd-graphene nanocatalysts for facile conversion of biomass-derived polyols to chemicals. ACS Nano 7, 1309–1316 (2013).Hong, C. et al. Graphene oxide stabilized Cu2O for shape selective nanocatalysis. J. Mater. Chem. A 2, 7147–7151 (2014).Reina, A. et al. Large area, few-layer graphene films on arbitrary substrates by chemical vapor deposition. Nano Lett. 9, 30–35 (2008).Wei, D. et al. Synthesis of N-doped graphene by chemical vapor deposition and its electrical properties. Nano Lett. 9, 1752–1758 (2009).Kim, K. S. et al. Large-scale pattern growth of graphene films for stretchable transparent electrodes. Nature 457, 706–710 (2009).Li, X. et al. Large-area graphene single crystals grown by low-pressure chemical vapor deposition of methane on copper. J. Am. Chem. Soc. 133, 2816–2819 (2011).Mattevi, C., Kima, H. & Chhowalla, M. A review of chemical vapour deposition of graphene on copper. J. Mater. Chem. 21, 3324–3334 (2010).Liu, W., Li, H., Xu, C., Khatami, Y. & Banerjee, K. Synthesis of high-quality monolayer and bilayer graphene on copper using chemical vapor deposition. Carbon 49, 4122–4130 (2011).Losurdo, M., Giangregorio, M. M., Capezzuto, P. & Bruno, G. Graphene CVD growth on copper and nickel: role of hydrogen in kinetics and structure. Phys. Chem. Chem. Phys. 13, 20836–20843 (2011).Gao, L., Guest, J. R. & Guisinguer, N. P. Epitaxial graphene on Cu (111). Nano Lett. 10, 3512–3516 (2010).Zhao, L. et al. Influence of copper crystal surface on the growth of large area monolayer graphene. Solid State Commun. 151, 509–513 (2011).Wood, J. D., Schmucker, S. W., Lyons, A. S., Pop, E. & Lyding, J. W. Effects of polycrystalline Cu substrate on graphene growth by chemical vapor deposition. Nano Lett. 11, 4547–4554 (2011).Primo, A., Atienzar, P., Sanchez, E., Delgado, J. M. & Garcia, H. From biomass wastes to large-area, high-quality, N-doped graphene: catalyst-free carbonization of chitosan coatings on arbitrary substrates. Chem. Commun. 48, 9254–9256 (2012).Primo, A., Sánchez, E., Delgado, J. M. & García, H. High-yield production of N-doped graphitic platelets by aqueous exfoliation of pyrolyzed chitosan. Carbon 68, 777–783 (2014).Primo, A., Forneli, A., Corma, A. & García, H. From biomass wastes to highly efficient CO2 adsorbents: graphitisation of chitosan and alginate biopolymers. ChemSusChem. 5, 2207–2214 (2012).Ravi Kumar, M. N. V. A review of chitin and chitosan applications. React. Funct. Polym. 46, 1–27 (2000).Rinaudo, M. Chitin and chitosan: properties and applications. Prog. Polym. Sci. 31, 603–632 (2006).Rinaudo, M. Main properties and current applications of some polysaccharides as biomaterials. Polym. Int. 57, 397–430 (2008).Latorre-Sanchez, M. et al. The synthesis of a hybrid graphene-nickel/manganese mixed oxide and its performance in lithium-ion batteries. Carbon 50, 518–525 (2012).Park, B. K. et al. Synthesis and size control of monodisperse copper nanoparticles by polyol method. J. Colloid Interface Sci. 311, 417–424 (2007).Lavorato, C., Primo, A., Molinari, R. & Garcia, H. Natural alginate as a graphene precursor and template in the synthesis of nanoparticulate ceria/graphene water oxidation photocatalysts. ACS Catal. 4, 497–504 (2014).Wu, S. et al. Electrochemical deposition of Cl-doped n-type Cu2O on reduced graphene oxide electrodes. J. Mater. Chem. 21, 3467–3470 (2011).Jiang, L. et al. Surface-enhanced Raman scattering spectra of adsorbates on Cu2O nanospheres: charge-transfer and electromagnetic enhancement. Nanoscale 5, 2784–2789 (2013).Sridhara Rao, D. V., Muraleedharan, K. & Humphreys, C. J. Microscopy Science, Technology, Applications and Education Vol. 2, 1232–1244Formatex, Badajos (2011).Lewin, A. H. & Cohen, T. The mechanism of the Ullman reaction. Detection of an organocopper intermediate. Tetrahedron Lett. 6, 4531–4536 (1965).Hassan, J., Sévignon, M., Gozzi, C., Schulz, E. & Lemaire, M. Aryl-aryl bond formation one century after the discovery of the Ullmann reaction. Chem. Rev. 102, 1359–1469 (2002).Ma, D., Cai, Q. & Zhang, H. Mild method for Ullman coupling reaction of amines and aryl halides. Org. Lett. 5, 2453–2455 (2003).Li, Y., Gao, W., Ci, L., Wang, C. & Ajayan, P. M. Catalytic performance of Pt nanoparticles on reduced graphene oxide for methanol electro-oxidation. Carbon 48, 1124–1130 (2010).Ong, W.-J., Tan, L.-L., Chai, S.-P. & Yong, S.-T. Heterojunction engineering of graphitic carbon nitride (g-C3N4) via Pt loading with improved daylight-induced photocatalytic reduction of carbon dioxide to methane. Dalton Trans. 44, 1249–1257 (2015).Luo, C., Zhang, Y., Zeng, X., Zeng, Y. & Wang, Y. The role of poly(ethylene glycol) in the formation of silver nanoparticles. J. Colloid Interface Sci. 288, 444–448 (2005).Wu, S.-H. & Chen, D.-H. Synthesis and characterization of nickel nanoparticles by hydrazine reduction in ethylene glycol. J. Colloid Interface Sci. 259, 282–286 (2003).Hou, Z., Theyssen, N., Brinkmann, A. & Leitner, W. Biphasic aerobic oxidation of alcohols catalyzed by poly(ethylene glycol)-stabilized palladium nanoparticles in supercritical carbon dioxide. Angew. Chem. Int. Ed. 117, 1370–1373 (2005).Dhakshinamoorthy, A., Navalon, S., Sempere, D., Alvaro, M. & Garcia, H. Reduction of alkenes catalyzed by copper nanoparticles supported on diamond nanoparticles. Chem. Commun. 49, 2359–2361 (2013).Ito, H., Watanabe, A. & Sawamura, M. Versatile dehydrogenative alcohol silylation catalyzed by Cu (I)-phosphine complex. Org. Lett. 7, 1869–1871 (2005).Rendler, S. et al. Stereoselective alcohol silylation by dehydrogenative Si-O coupling: scope, limitations, and mechanism of the Cu-H-catalyzed non-enzimatic kinetic resolution with silicon-stereogenic silanes. Chem. Eur. J. 14, 11512–11528 (2008).Cristau, H. J., Cellier, P. P., Spindler, J. F. & Taillefer, M. Highly efficient and mild copper-catalyzed N- and C-arylations with aryl bromides and iodides. Chemistry 10, 5607–5622 (2004).Shafir, A. & Buchwald, S. L. Highly selective room-temperature copper-catalyzed C-N coupling reactions. J. Am. Chem. Soc. 128, 8742–8743 (2006)

    Measurement of Trilinear Gauge Couplings in e+ee^+ e^- Collisions at 161 GeV and 172 GeV

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    Trilinear gauge boson couplings are measured using data taken by DELPHI at 161~GeV and 172~GeV. Values for WWVWWV couplings (V=Z,γV=Z, \gamma) are determined from a study of the reactions \eeWW\ and \eeWev, using differential distributions from the WWWW final state in which one WW decays hadronically and the other leptonically, and total cross-section data from other channels. Limits are also derived on neutral ZVγZV\gamma couplings from an analysis of the reaction \eegi

    Search for neutral heavy leptons produced in ZZ decays

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    Weak isosinglet Neutral Heavy Leptons (νm) have been searched for using data collected by the DELPHI detector corresponding to 3.3 × 106 hadronic Z0 decays at LEP1. Four separate searches have been performed, for short-lived νm production giving monojet or acollinear jet topologies, and for long-lived νm giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z0 → νmν̄) of about 1.3 × 10-6 at 95% confidence level for νm masses between 3.5 and 50 GeV/c2. Outside this range the limit weakens rapidly with the νm mass. The results are also interpreted in terms of limits for the single production of excited neutrinos. © Springer-Verlag 1997

    Study of B0_s anti-B0_s oscillations and B0_s lifetimes using hadronic decays of B0_s mesons

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    Oscillations of B0s mesons have been studied in samples selected from about 3.5 million hadronic Z decays detected by DELPHI between 1992 and 1995. One analysis uses events in the exclusive decay channels: B0s -> Ds- pi+ or Ds- a1+ and B0s -> anti-D0 K- pi+ or anti-D0 K- a1+, where the D decays are completely reconstructed. In addition, B0s anti-B0s oscillations have been studied in events with an exclusively reconstructed Ds accompanied in the same hemisphere by a high momentum hadron of opposite charge. Combining the two analyses, a limit on the mass difference between the physical B0s states has been obtained: Delta(m_B0s) > 4.0 ps^{-1} at the 95% C.L. with a sensitivity of Delta(m_B0s) = 3.2 ps^{-1}. Using the latter sample of events, the B0s lifetime has been measured and an upper limit on the decay width difference between the two physical B0s states has been obtained: tau(B0s) = 1.53^{+0.16}_{-0.15}(stat.) +/- {0.07}(syst.) ps \Delta\Gamma(B0s)/\Gamma(B0s) < 0.69 at the 95% C.L. The combination of these results with those obtained using Ds+- lepton-+ sample gives: Delta(m_B0s) > 4.9 ps^{-1} at the 95% C.L. with a sensitivity of Delta(m_B0s) = 8.7 ps^{-1}. tau(B0s) = 1.46 +/- 0.11 ps and \Delta\Gamma(B0s)/\Gamma(B0s) < 0.45 at the 95% C.L.Comment: 42 pages, 13 figure
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